No abstract

Petroleum contamination in soil fields is a serious problem, particularly in countries that produce, transport, and refine oil. Phytoremediation is a promising approach for the cleanup of soil contaminated with petroleum hydrocarbons (PHCs) and heavy metals (HMs). For this purpose, this study was conducted to identify gene expression profiles for two related genes in response to petroleum stress in maize leaves at two contaminated sites. Two sites were chosen to collect polluted soil with oily residues: AL-Daura power station and AL-Daura oil refinery in Baghdad province. The soil was subjected to chronic pollution for many years. In addition, one unpolluted site was chosen for comparison as control around 4 Km upwind from ALDaura thermal power station. The gene expression of Opr1 and Pao1 genes in addition to ZmAct as reference gene was analysis in the maize leaves using RT-PCR. All data were statistically analyzed using analysis of variance, and treatment means were differentiated using the Least Significant Difference (LSD) test at P ≤ 0.05. The expression of Opr1 and Pao1 genes in maize leaves was overexpressing with 42.86 and 10.25 folds at refinery soil, respectively, while at power station soil increased with 5.16 and 5.04 folds, respectively but not differ significantly from control soil. The study show that the Real-time PCR analysis confirmed the expression patterns of the Opr1 and Pao1 genes, which play critical roles in mediating plant tolerance to petroleum stress.

The importance of studying pre-sowing seed treatment lies in the possibility of regulating the rate of seed germination, the intensity of their growth and obtaining root exudates in biotechnology. The effect of three pre-sowing treatment methods was examined (control – washing with running water; the first method – washing with 0.05% sodium permanganate solution; the second method – 30 se­conds in 70% ethyl alcohol (C2H5OH) and 30 minutes in 5% sodium hypochlorite (NaOCl); the third method – 5 minutes in 70% C2H5OH and 40 minutes in 5% NaOCl) on the growth rate, germination rate, excretion rate of seeds of wheat and peas and composition (of protein, carbohydrate, amino acid content) of root exudates from the first to the third day of growth in order to obtain root exudates. It was revealed that the same pre-sowing treatment of wheat and pea seeds has a different effect on the rate and variability of seedling growth from the first to the third day, as well as on the qualitative and quantitative composition of root exudates. It was shown that pre-sowing treatment of wheat and pea seeds for 5 minutes with 70% ethanol followed by treatment with sodium hypochlorite (a “hard” treatment method) accelerates seedling growth and seed germination. This method of treatment reduces the intensity of excretion of root exudates and composition in wheat, but it increases the intensity of excretion in peas. The discovered effects can be explained by hormesis. Additionally, the third method of pre-sowing seed treatment can be used in root technologies for obtaining root exudates.